1. Field of the Invention
The present invention mainly relates to a portable electronic device for locking and unlocking vehicle doors by remote control operation.
2. Background Art
In recent years, vehicles have had higher functions and been diversified, which accordingly has increased devices for locking and unlocking vehicle doors by remote control operation with the use of a transmitter using infrared rays or electric wave in addition to doors locked and unlocked directly by a key.
Electronic devices used for this purpose are often stored in a vehicle or used outside. Therefore, these transmitters are strongly required to have dustproof and waterproof properties. For example, Japanese Patent Unexamined Publication No. 7-297565 and Japanese Patent Unexamined Publication No. 9-8474 describe conventional transmitter and receiver.
However, in the case of conventional electronic devices, in order to enhance dustproof and waterproof properties, the outer shape of the device has to become larger. Therefore, it has been difficult to miniaturize such devices.